Screen grid tube circuit



May 15, 1934. a. D. H. TELLEGEN 1,959,010

' SCREEN GRID TUBE CIRCUIT Filed June 28, 1930 l l l l l l INVENTORBERNARDUS D. H. TELLEGEN ATTORNEY Patented May 15, 1934 PATENT OFFICESCREEN GRID TUBE CIRCUIT Bernardus Dominicus Hubertus Tellegen,Eindhoven, Netherlands, assignor to Radio Corporation of America, acorporation of Delaware Application June 28, 1930, Serial No. 464,467 Inthe Netherlands August 9, 1929 Claims.

The present invention relates to improvements in, or relating to,circuit arrangements for screen grid tubes.

In the usual circuit arrangements for screen grid tubes the screen gridelement is connected through a resistance to a point having a positivepotential with respect to the cathode. The current passing through thescreen grid being subject to variations, the voltage in the screen grid,in the said circuit arrangement, may be subject to fluctuations byreason of the potential drop in the resistance. This is an undesiredphenomenon which affects the quality of reception.

According to this invention, in order to obvlate the said disadvantageof screen grid is not connected through an ordinary resistance, butrather through a neon glow lamp, or other discharge tube of similarcharacteristic, to a suitably chosen point of the circuit arrangement,

preferably a point of positive potential. Thus, independently of thecurrent intensity in the screen circuit, the voltage of the screen gridis constant, as, practically, the voltage across the terminals of a neonglow lamp is independent of the current intensity in the lamp.

The novel features which I believe to be characteristic of my inventionare set forth in particularity in the appended claims, the .inventionitself, however, as to both its organization and method of operationwill best be understood by reference to the following description takenin connection with the drawing in which I have indicateddiagrammatically one circuit organization whereby my invention may becarried into effect.

In order that the invention may be clearly understood and readilycarried into effect one embodiment of the invention will be describedmore fully with reference to the accompanying drawing, in which such anembodiment is illustrated by way of example.

Referring to the single figure, l designates a screen grid tube havingits input circuit connected to a source of high frequency energy to beamplified, and having a cathode 2, a control grid 3, a screen grid 4 andan anode 5. The cathode 2 is connected to the anode 5 through a sourceof current 6 and the primary 6' of a transformer 7, the latter beingconnected to a subsequent stage. A neon lamp 8 is connected between thescreen grid 4 and a predetermined point 9 of the source of current 6, orof a resistance 9 shunted across the terminals of the source of current.

Thus, the voltage between the point 9 and the screen grid 4 remainsconstant independently of the current intensity in the lamp 8.Obviously, circuit arrangements distinct from that shown in the drawingare also possible. Thus, for example, the neon lamp may be connectedbetween the screen grid and the cathode, the voltage between the cathodeand the screen grid being in this case determined by the operatingvoltage of the glow lamp. Various means known per se may be used forensuring the ignition. The invention practically permits of anypotential fluctuation of the screen grid being eliminated.

While I have indicated and described one arrangement for carrying myinvention into effect, it will be apparent to one skilled in the artthat my invention is by no means limited to the particular organizationshown and described, but that many modifications may be made in thearrangement, without departing from the scope of my invention as setforth in the appended claims.

What I claim is:

1. A method of operating an electron discharge tube provided with ascreen element disposed between the control electrode and anode of thetube, which consists in establishing a gaseous path between the screenelement and a point of positive potential having a predetermined valuewhereby potential fluctuations in the screen element circuit areeliminated.

2. In combination with a screen grid tube circuit a source of highfrequency energy to be amplified connected to the input of said circuit,a source of anode potential in the output circuit of the tube, and a gasdischarge path between the screen element and said source of potential.

3. In combination an electron discharge tube provided with a cathode,control electrode, anode, and a screen element, a source of highfrequency energy connected to the control electrode and cathode, asource of potential in the anode circuit of the tube, an impedanceconnected across said anode source, and a gas discharge tube connectedbetween the screen element and a predetermined point of said impedance.

4. A relay circuit comprising a thermionic tube having input electrodes,output electrodes, and an auxiliary electrode, a source of signalcurrent connected with said input electrodes, a translating circuitconnected with said output electrodes, said translating circuitincluding a source of potential, and means for applying a constantpotential to said auxiliary electrode comprising a discharge tubeconnecting said auxiliary electrode to a point on said source.

cuit, and means for maintaining the relaying characteristics of saidtube constant comprising a discharge device connecting said auxiliaryelectrode to a point on said resistance.

BERNARDUS DOMINICUS HUBERTUS TELLEGEN.

